High-temperature hydrocarbon conversion process



Jan.`25, '1949. s. c. EAsTwooD 2,460,219

HIGH TEMPERATURE HYDROCARBON CONVERSION PROCESS I riledFeb. 28, 194sFLUE HS OUTLET MHIWFQLD 60N VR TUE )lle/rr mr/msg f-Zwa naar EN TOR.

-GENT OR ATTORNEY M50/mwah aN y mes Patented Jan. 25, 1949HIGH-TEMPERATURE HYDROCARBON CONVERSION PROCESS Sylvander C. Eastwood,Woodbury, N. J., assignor to Socony-Vacuum Oil Company, Incorporated, acorporation of New York Application February 28, 1948. Serial No. 11,893

9 Claims. A( Cl. 196- 52) 'This invention deals with a process forconducting the conversion of fluid hydrocarbons in the presence of amoving particle form solid contact material'which may or may not becatalytic in nature. The invention has particularly to do with ahydrocarbon conversion process wherein the reaction is endothermic andthe heat of reaction is supplied into the reaction zone as sensible heatin the hot contact material charge whichenters the reactor at atemperature level which is substantially above the average conversiontemperature and often above a safe level at which it is practical tomechanically convey the solid material in conventional conveyorequipment. Exemplary of such processes is the high temperature catalyticcracking conversion of hydrocarbons to form high percentages of aviationgasoline and C4 fractions at temperatures of the order of M100-1200* F.and pressures usually ranging upwards from atmospheric pressure. Anotherprocess is the dehydrogenation of butene to di-oleilns at temperaturesof the order of 1000-1300 F. in the presence of a dehydrogenationcatalyst such as chromlc oxide on activated alumina. Still anotherreactor is the pyrolysis of pentene-2 to butadiene at temperatures ofthe order of 12001300 F. Another process is thev manufacture of ethyleneby the cracking of heavier hydrocarbons such as gas oils or by thecracking of propane or ethane at temperatures of the order of 1400F.-1800 F. A process of particular importance is the catalytic crackingconversion of high boiling petroleum residuums and the like to lowerboiling hydrocarbon products at average reaction temperatures of theorder of 800-1000 F. In the case of the latter reaction it is desirableto supply in the catalyst feed not only the heat for the crackingreaction but also the latent heat required to vaporize the liquidhydrocarbon feed. This often requires an inlet catalyst temperaturesubstantially above the average conversion temperature and substantiallyabove a level at which it is practical to mechanically convey thecatalysts.

A particularly desirable continuous process for converting hydrocarbonsin the presence of a moving catalyst is one wherein the catalyst owscyclically through a conversion zone in which it flows downwardly bygravity as a substantially compact column while being contacted withfluid hydrocarbons to elect the conversion thereof and then through aregeneration zone in which it also moves as a compact column while beingcontacted with a combustion supporting gas to burn off from thecatalystla carbonaceous contaminant deposited thereon in the conversionzone.

An important practical difficulty arises in attempting to conduct suchprocesses as enumerated above in the so-called moving bed type ofprocesses. Such moving bed type processes for proper operation requirethe use of a granular or particle form contact material as distinguishedfrom powdered contact material and it is of the utmost importance inmoving bed processes to limit the amountof catalyst attrition to iinesto an absolute minimum. In order to attain this objective it has beenfound necessary in such systems wherein cyclic ow of the contactmaterial is involved to utilize mechanical conveyors to complete thecyclic event. One of the most satisfactory types of mechanical conveyorsfor this purpose is the continuous bucket elevator which is adapted totransfer solid particles from one level to another with a minimum ofbreakage and attrition of said solid particles. However, in processes ofthe type described hereinabove, the required contact material inlettemperature to the hydrocarbon convertor is often so high that attemptsto mechanically convey the contact materials at such temperatures wouldresult in failure and very rapid wear of the metal parts of themechanical conveyor. It has been suggested heretofore that in processesof the type herein involved, the heat required for the hydrocarbonconversion may be economically provided by permitting the catalysttemperature to rise in the regeneration and by then passing the hotregenerated catalyst directly into the reaction zone. Prior artpublications have shown diagrams of regenerators positioned verticallyabove hydrocarbon convertors so that the hot regenerated catalyst owsdirectly by gravity from the regenerator to the reactor. Such anarrangement has the serious disadvantage that on a practical commerclalscale the heavy regenerator vessel must be supported high in the air atelevations running into two and three hundred feet, thereby greatlyincreasing the cost of the structural support and vices are highlyundesirable because they cause` crushing of the catalyst particles andrapid formation of nes.

Because of these serious dimculties it has been commercial practice toposition the reactors and regenerators side by side and to employmechanical conveyors to transport the catalyst to locations from whichit may ow into these vessels. In such arrangements, the regeneratedcatalyst is mechanically conveyed to a surge hopper above the reactionzone from which it ows by gravity into the reaction zone. Because of thenecessity of mechanically conveying the hot regenerated catalyst, it hasbeen found to be infeasible to conduct many operations which wouldrequire a catalyst inlet temperature to the conversion zone which isabove the practical mechanical convey- 'ing level. It has been foundthat a practical mechanical conveying temperature for conventionalmechanical conveying equipment adapted for high temperature work shouldbe preferably below about 1000 F. and in any event below about 1100 F.

A major object of this invention is the provision of a continuouscatalytic process for conversion of hydrocarbons which overcomes theabove mentioned difliculties.

A specic object is the provision of a process for conducting endothermicconversions of uid hydrocarbons in the presence of a moving mass ofparticle form solid contact material at temperatures which are at leastpartially substantially above those at which it has been heretoforefound practical to convey solid particles.

Another specific object is the provision of an improved cyclic processfor the high temperature conversion of saturated fluid hydrocarbons toethylene containing products.

These and other objects of this invention will become apparent from thefollowing discussion thereof.

The invention may be most readily under-` stood by reference to thesingle drawing attached hereto which shows diagrammatically anelevational view of a preferable continuous cyclic conversion system forconducting the method of this invention.

In the drawing we nd a vertical conversion vessel I0, having a verticalgravity catalyst feed leg II connecting into its upper end and adischarge conduit for catalyst I2 connecting into its lower end andbearing a catalyst flowy control valve I3. Alongside of the convertor Iis a regeneration vessel I4 provided with a catalyst inlet duct I at itsupper end and a catalyst outlet conduit I6, bearing a flow control valveat its lower end. A catalyst surge chamber I1 is positioned at the upperend of vessel I4 and a catalyst surge hopper I'8 is positioned at theupper end of the gravity feed leg I I for reactor supply. A suitablemechanical conveyor I9 is provided to carry spent catalyst from theconvertor I0 to a location wherefrom it may flow by gravity via duct I5to the regenerator catalyst surge chamber I1. Similarly a mechanicalconveyor 20 is provided to convey hot regenerated catalyst from theregenerator I4 to a location above the convertor surge hopper I8 fromwhich location catalyst may flow by gravity via duct 2l to the surgehopper I8. 'Ihe conveyors I9 and 20 are driven by motors 22 and 22'respectively and should be of a type adapted for high temperatureservice and for conveying particle form catalyst without excessiveattrition, crushing and breakage thereof. A continuous bucket elevatorhas been found to be very satisfactory for this purpose but theinvention is not contemplated as being restricted to only this type ofmechanical conveyor.

The regenerator I4 shown is of the multistage type consisting ofalternate burning zones 22 and cooling zones 24. Air may be introducedfrom a manifold 25 into each burning zone 23 via pipes 26 and after :dowthrough the catalyst may be withdrawn via pipes 21 and manifold 2l. Acooling fluid may be introduced into each cooling zone from manifold 29via pipes I0 into suitable heat transfer tubes (not shown) within thecooling zones. The cooling fluidv may be withdrawn from the heattransfer tubes via pipes 22 to a common outlet manifold 22. Aregenerator of this type is described in United States Patent 2,417,399,which was issued on March ll, 1947, to Simpson et al. While this is apreferred form of regenerator, it is contemplated that within the scopeofthe present invention other regenerators adapted for burningregeneration of catalysts under controlled temperature conditions may beemployed.

'I'he convertor I'II is provided with a reactant inlet 35 near its lowerend and with a purge gas l inlet 31 a spaced distance below the inlet26.

Suitable vapor distribution devices well known to the art may beprovided to insure proper distribution of the inletvapors into thecatalyst column within the vessel I9. Also suitable baffling may beprovided near the bottom of the vessel I0 to promote uniformity ofcatalyst withdrawal from all portions of the vessel crosssectional area.A suitable battle system for this purpose is described in United StatesPatent 2,412,136, issued on December 3, 1946, to Evans et al. Across theupper section of vessel I0 are provided two vertically spaced horizontalpartitions 39 and 40 which dene a seal chamber 4I and a catalyst finalburning chamber 42. Uniformly distributed conduits 49 depend frompartition 39 for flow of catalyst from final burning chamber 42 to sealchamber 4I and similar conduits 44 depend from partition 40 for flow ofcatalyst from seal chamber 4I to the reaction chamber 43. The conduits44 also define a gassolid disengaging space 45 immediately belowpartition 40. A reaction product vapor outlet conduit 41 connectsthrough the vessel wall into this disengaging space. A row of invertedgas inlet distributing troughs 5I (one being shown) is positioned withinfinal burning zone and these troughs are supplied with air via a row ofpipes 52. Spaced vertically above and below troughs 5| are rows ofcollector troughs 54 and 55 from which gas is Withdrawn via pipes 5B and51 respectively. Similar distributing troughs 58 supplied by pipes 59and collector troughs 50 and 5I with outlet pipes 52 and 53 respectivelyare provided in the surge hopper I8.

In operation hot regenerated catalyst passes from hopper I8 down throughthe elongated feed leg Il into the upper end of chamber 42 and thenthrough seal chamber 4I into reaction chamber 43. The hopper I8 may beat substantially atmospheric pressure whereas the pressure in sealchamber 4I is somewhat above (say one half pound per square inch) thatin the upper section of reaction chamber 42. The feed leg II should beof sufiicient length to overcome this pressure differential. Such a feedleg is described in United States Patent 2,410,309, issued to Simpson etal. on October 29, 1946. The catalyst flows by gravity downwardlythrough chambers 42, 4I and 43 as a substantially compact column. Fluidreactants introduced at 2l pass through the catalyst column to becomeconverted to lower boiling hydrocarbons -and the gaseous products arewithdrawn at 41. It will be understood that the term gaseous as usedherein in describing and claiming this invention is used in a broadsense as meaning that the material involved exists in the gaseous phaseunder the conditions of temperature and pressure involved regardless ofwhat may be its normal phase under ordinary atmospheric conditions. Ifthe reactant charge Ais a high boiling liquid charge, for example apetroleum reslduum, it may be introduced into the upper section ofchamber 43 through manifold 80, header 8i .and spray nozzles 82, and thegaseous products will in -that event be withdrawn from the lowersectionof chamber 43 at 36. The reactions towards which this invention isdirected are endothermic and in order to supply the heat of reaction thecatalyst is introduced into chamber 43 above the desired averagereaction temperature and is Withdrawn at l2 below the desired averagereaction temperature. For example, in a high temperature conversion of aliquid residuum petroleum charge to lower boiling gaseous products thecatalyst may enter the reaction chamber 43 at a temperature within therange 1100 to 1200 F. and the drop in catalyst temperature in passingthrough the conversion zone may vary from about 10D-300 F. or moredepending upon the particular operating conditions, the severity of thereaction and the catalyst to oil ratio. In .a typical operation thecatalyst may enter at 1200 F. and leave the convertor via conduit l24atabout 950 F. This latter temperature is sufficiently low to permitmechanlcal conveying of the spent .catalyst particles without furthercooling. so the spent catalyst may be directly transferred by mechanicalconveyor I9 to the upper end of duct l5 through which it may ilow bygravity .to the regenerator catalyst surge zone il. The catalyst thenpasses downwardly through the regenerator I4 as a substantially compactvcolumn while being subjected to an oxygen containing gas such as air toburn off the carbonaceous contaminant deposited on the catalyst in theconvertor. Heat is removed from the catalyst in the cooling zones 24 soas to maintain it at a temperature level below a heat damaging level andabove that minimum required for practical contaminant burning rates. Theheat damaging temperature will vary depending upon the nature of thecontact material involved being abovey about 1150-1250 F. for many claycatalysts and above about 1350-1500" F. for synthetic silica-aluminaVgel catalysts. The rate of air introduction into the burning zonesand/or the rate of catalyst ilow through the regenerator is socontrolled that the catalyst discharging from the lowermost burning zonestill contains a residual carbonaceous deposit which is within the rangeabout 0.2 to 0.7 percent by weight contaminantbased on the catalyst overand above any deposit which ls normally left on the "freshly regeneratedcatalyst entering the reaction zone 43. The exact amount of contaminantleft on the catalyst will depend upon the catalyst temperature risedesired in zones I8 or 42 as discussed hereinafter and upon theallowable residual contaminant on th-e freshly regenerated catalystentering zone 43. Usually for catalytic cracking of gas oils or heavierhydrocarbons, the allowable residual carbon content on the freshlyregenerated catalyst entering reaction zone 43 will be of the order ofabout 0.1 to 1.0% by weight of lthe catalyst depending upon theparticular reaction and the operating conditions. s

In some operations the regeneration may be so controlled that thetemperature of the catalyst may be at a level suitable for mechanicalconveying in which event it may be passed directly to the mechanicalconveyor 20 without intermediate cooling. This is usually the case alsowhen single stage regenerators provided with cooling tubes throughouttheir length are employed. .)n the other hand the catalyst leaving thelast burning zone 23 may be above a temperature at which it may bepractically mechanically conveyed, for example 1200" F. or even higher,in

which event it is cooled in cooling zone lo to a suitable mechanicalconveyingl temperature which is below about 1100 F. and preferably at orbelow about 1000 F. The catalyst at 1000 F., for example, is thenmechanically conveyed to the inlet end of duct 2| through which it ilowsinto hopper i8. The catalyst entering hopper i8 at 1000 F. is because ofthe mechanical conveyor maximum temperature limitation below thetemperature required for its introduction into lzone 43, namely 1200 F.in the exemplary operation under discussion. Air is introduced via pipes59 and distributed into the catalyst bed by troughs 58, and is passedthrough thecatalyst bed in hopper I8 to the collectors 60 and 6l so asto accomplish burning of the 'residual contaminant in the absence ofheat removal by any other heat exchange fluid. The catalyst temperatureis thereby increased due to the heat liberated by contaminantcombustion, and the rate of air introduction is controlled so as Itoburn sulcient contaminant deposit to heat the catalyst to the requiredtemperature of 1200o F. As stated above, the amount of contaminantremaining on the catalyst entering hopper i8 is maintained equal to thatrequired to accomplish this heatingT of the catalyst in hopper I8 overand above any allowable residual deposit on the catalyst entering thereactor zone 43. The required amount of residual contaminant on thecatalyst entering hopper I8 may be easily calculated by methods known tothose skilled in the art once the particular operating temperatureconditions and the allowable residual deposit on the cataylst enteringthe hydrocarbon reaction zone have been set for the particularhydrocarbon conversion reaction involved. In general, it has been foundthat for most endothermic catalytic hydrocarbon conversion reactions theamount of contaminant on the catalyst leaving the principal regenerationzone should be within the range 0.2-0.7 percent by weight of thecatalyst calculated as carbon over and above any residual deposit on thefreshly regenerated catalyst as it enters the hydrocarbon conversionzone. The heated freshly regenerated catalyst then passes by gravityinto the seal zone 4l and then into the reaction zone 43. An inert sealgas such as steam or flue gas is introduced into the seal zone 4| viapipe 15 at a rate controlled by diaphragm valve 16 and differentialpressure controller Il which will maintain an inert gas pressure in sealzone 4I slightly higher (one quarter to one half pound per square inch)than the pressure within lthe upper section of zone 43, therebypreventing escape of reactants through the catalyst feed leg il. Whenthe hopper i8 is employed as described hereinabove, the zone 42 may beeliminated, leaving a seal zone only at the upper end of vessel i0. t

It will be apparent that by the method of this V7 invention itbecomespossible to conduct many reactions requiring catalyst reactorinlet temperatures substantially above the level at which conventionalmechanical conveyors can be employed. and this without any increase inthe overall height of the cyclic system and with an actual decrease inthe required size of the regenerator. It will be noted that the catalystsurge hopper I8 is already employed in commercial cyclic conversionsystems of the moving bed type so that present commercial units may beadapted for the method of this invention simply by adding gasdistributing and collecting troughs and connecting pipes to the alreadyexisting reactor surge hopper.

When the reactor surge hopper is employed as a iinal burning zone asdescribed hereinabove. the regeiieration pressure in the hopper is nearatmospheric due to the fact that the conveyors are most convenientlyoperated at atmospheric pressure. In some operations it is desirable inorder to obtain more rapid burning of the residual contaminant depositto conduct the final burning step under pressure. In such operations. itis preferable to employ zoneV 42 as the ilnal burning zone instead ofhopper I8, because the feed leg Il is then available to feed thecatalyst into the regeneration zone operating under superatmosphericpressure. In this operation the air is introduced into zone I2 via pipes52 and the gaseous regeneration products are withdrawn via pipes 56 and51. When zone 42 is so employed it is important to maintain the inertgas pressure within seal zone Il not only above the pressure in reactionzone I3 as described hereinabove but also above the pressure within zone42. 'I'his is accomplished by means of the auxiliary inert gas inlet 85through which additional inert gas is introduced as controlled bydiaphragm valve 88 and differential pressure controller 81 whenever therate of inert gas introduction -through valve 16 is insuiilcient tomaintain the pressure in zone 4i above that in zone I2.

It will be understood that the dimensions of the apparatus employed, therates of reactant and solid flow, and the type of solid material andheat exchange gas employed are subject to wide variation depending uponthe particular process to which this invention is applied. In general,the reaction zone should be of such size as will permit the proper timeof reactant contact with the suitable solid material therein for anygiven process. The final burning zone should be of sutlicient volume toprovide a catalyst residence time long enough to accomplish the desiredheating of the catalyst by the contaminant burning. The required volumeof final burning zone may be decreased by the use of pressure in thiszone.

The reactant space velocity in the conversion zone will, of course, varydepending upon the particular operation involved. Where petroleum gasoils are to be converted to products containing high amounts of aviationgasoline and four carbon atom hydrocarbons the oil space velocity mayvary from about 0.5 to 5.0 volumes of oil charge (measured as a liquidat 60 F.) per hour per volume of catalyst in the conversion zone(measured as a substantially compact flowing column). The catalyst tooil charge ratio to the convertor in such an operation may fall withinthe range about 1 to 10 parts by weight of catalyst per part by weightof oil charged. In the case the pyrolytic conversion of ethane toethylene over refractory contact material particles at inlet solidmaterial temperatures of the order of 1750-1800 F. at about 5-20 poundsper Square inch pressure, a solid material throughput amounting to aboutrto 15 pounds of solid per pound of ethane charge is satisfactory. 'I'hevolume of the reaction zone 24 should be such as to provide a reactantresidence time of about 1.0 to 1.7 seconds.

` The type of solid material used may vary from an inert solid such ascorhart material. a fused alumina, which may be used for ethylenemanufacture to an adsorbent type catalytic material vwhich may be usedfor catalytic dehydrogenation reactions and for catalytic crackingreaction. Such catalytic materials may take the form of natural ortreated clays, bauxites, inert carriers containing deposited metallicoxides such as deposits of the oxides of molybdenum, chromium ortungsten, or certain synthetic associations of silica, alumina or silicaor alumina to which small percentages of other materials such asmetallic oxides may be added for special purposes. In general, it hasbeen found that the particle size of such contact materials should fallbroadly within -the range about .006 lto 1.0 inch average diameter andpreferably within the range about 0.03 to 0.5 inch average diameter. Itshould be understood that the expression "suitable particle form contactmaterial as used in describing and in claiming this invention is used ina sense sumciently broad to cover either socalled catalytic ornon-catalytic materials which may be found suitable for the particularreaction involved. The term is to be considered as llmited, however,only to those solid materials which have physical 'and chemicalcharacteristics making them suitable for the particular processinvolved. Thus, for example solids. which would enter substantially intothe main reaction or which would be decomposed or otherwise damagedunder the reaction conditions involved, are not intended to be includedin the term.

In the claiming of this invention the expressions suitable conversiontemperature and range of suitable conversion temperature" are intendedto mean a temperature or range of temperatures which are suitable forconducting the particular reaction involved at a practical rate and topractical yields of the desired products.

- AIt should be understood that the foregoing description of the methodof this invention and examples of its applications and of the apparatusto which it may be applied are merely exemplary in character and are notintended to limit the scope of this invention except as it is limited inthe following claims.

I claim:

l. A continuous process for conducting endothermic conversions of fluidhydrocarbons at elevated temperatures in the presence of a suitablecontact material consisting of particles of substantial size asdistinguished from powdered material which process comprises:introducing said contact material into the upper section of a confinedconversion zone at a temperature suitable for supporting the conversionof said fluid hydrocarbons and for supplying at least most of the heatof reaction, passing said contact material downwardly through saidconversion zone while contactingit kwith said hydrocarbons to effect theconversion thereof with resultant deposition of a carbonaceouscontaminant deposit on said contact material, withdrawing the usedcontact material from the lower section o'f said conversion zone andpassing it to av mechanical conveying zone at a temperature at which itmay be practil cally mechanically conveyed. maintaining a confinedburning zone separate from said conversion zone, mechanically conveyingsaid used contact material to a location from which it may flow intosaid burning zone, passing said contact material downwardly through saidburning zone, passing a combustion supporting gas into contact with saidcontact material in said burning zone to effect burning of a substantialportion of butless than all of said contaminantdepositfrom saidcontactmaterial, passing the contact material bearing a residual portionof the original contaminant deposit from said burning zone to a conilnedconveying zone and controlling the temperature of said contact materialpassing to said last named conveying zone at a level at which thecontact material may be practically mechanically conveyed, maintaining aconflned final burning zone above said conversion zone, conveying saidcontact material bearing said residual portion of the originalcontaminant deposit to a location from which it may flow into said finalburning zone, passing said contact material through said final burningzone and eiecting an increase in its temperature to a level which issuitable for supporting said hydrocarbon conversion and for supplying atleast most of the heat absorbed by the hydrocarbon reaction by burningoff at least a substantial portion of the residual contaminant depositwith an oxygen containing gas and passing the contact material bygravity ow 'from said final burning zone into the upper section of saidconversion zone as aforesaid.

2. In a continuous process for endothermic conversions of fluidhydrocarbons at elevated temperatures in the presence of a movingparticle form solid contact material, wherein the heat of reaction issupplied at least mostly by the contact material thereby requiring aninitial contact material temperature substantially above that at whichit can be practically mechanically conveyed the improved method whichcomprises: passing said contact material as a substantially com-pactcolumn downwardly through a confined conversion zone while contacting itwith said fluid hydrocarbons to effect the conversion thereof, wherebyav carbonaceous contaminant is deposited on said contact material andthe temperature of said contact material is decreased due to heatadsorption by said conversion to a level at which the contactmaterialmay be practically mechanically conveyed, maintaining a coniined burningzone separate from and along side of said conversion zone, withdrawingspent contact material from said conversion zone and mechanicallyconveying said contact material upwardly to a location suitable for itsflow into said burning yzone, passing said spent contact material as asubstantially compact column downwardly through said burning zone,passing a combustion supporting gas into contact with said contact material in said burning zone to effect burning of an version zone,mechanically conveying said contact material bearing said residualcontaminant deposit to a location from which it may flow by gravity intosaid iinal burning zone, passing said contact material downwardlythrough said ilnal burning zone as a substantially compact column whilecontacting it with a combustion supporting gas to effect the burning offof said residual contaminant deposit, eilecting the removal of at leasta major portion of the heat released by contaminant burning in saidilnal burning zone as increased sensible heat in the contact material soas to thereby increase the contact material temperature to a levelsuitable for supplying in the contact material at least the major partof the heat required for the endothermic hydrocarbon conversion in saidconversion zone, said level being substantially above that at which thecontact material can be practically mechanically conveyed and flowingsaid contact material fromsaid final burning zone by gravity to saidconversion zone to supply said column of contact material therein.

3. In a continuous process for endothermic catalytic conversions offluid hydrocarbons to lower boiling hydrocarbons at elevatedtemperatures in the presence of a moving particle form solid catalystwherein at least the major portion of the heat of reaction is suppliedas sensible heat in the catalyst charge thereby requiring a catalystcharge temperature substantially above that at which the catalysts canbe practically mechanically conveyed the improved method whichcomprises: introducing freshly regenerated catalyst into the uppersection of a confined conversion zone and passing said catalyst as asubstantially compact column of gravltating particles downwardly throughsaid confined conversion zone while contacting it with said fluidhydrocarbons to effect the conversion thereof to lowerwboilinghydrocarbons whereby a carbonaceous contaminant deposit forms on saidcatalyst and the temperature of said catalyst is decreased, due toabsorption of heat therefrom for said hydrocarbon conversion, to alevelv at which the catalyst may be practically mechanically conveyed,maintaining a regeneration zone apart from said conversion zone,withdrawing spent catalyst from the lower section of saidl conversionzone and mechanically conveying it to a location from which it may iiowby gravity into the upper section of said regeneration zone, passingsaid catalyst as a substantially compact column downwardly through saidregeneration zone, burning off contaminant deposit from said catalyst bycontacting said catalyst moving through said regeneration zone with anoxygen containing gas until the amount of residual deposit on saidcatalyst is within the range about 0.2 to 0.7 percent by Weight of saidcatalyst in addition to any deposit left on the freshly regeneratedcatalyst entering said conversion zone, passing a fluid other than saidcombustion supporting gas in heat exchange relationship with said`catalyst during its passage through said regeneration zone to remove asubstantial portion of the heat liberated by contaminant burning and tocontrol the temperature of said catalyst below a level which would causeheat damage to said catalyst, withdrawing from the lower section of saidregeneration zone the partially regenerated catalyst bearing a residualcontaminant deposit of from about 0.2-0.7 percent by weight of thecatalyst in addition to any deposit left on the freshly regeneratedcatalyst entering the conversion zone and passing said catalyst at atemperature at which it can be practically mechanically conveyed to aconilned mechanical conveying zone, maintaining a substantially compactcolumn of said partially regenerated catalyst in a conilned ilnalburning zone above said conversion zone, mechanically conveying saidcatalyst to a location from which it may ilow by gravity to said iinalregeneration zone, ilowing said catalyst by gravity into said ilnalburning zone to supply said column there in, effecting an increase inthe temperature oi' said catalyst to a level which is substantiallyabove that at which it can be practically mechanically conveyed andwhich is sumciently high to insure supply of the heat required i'or saidhydrocarbon conversion as sensible heat in the catalyst by contactingsaid catalyst in said ilnal burning zone with a combustion supportinggas in the absence of heat removed by any other iluid medium to burn oi!from said catalyst within the range of 0.2 to 0.7 percent of saidresidual deposit, and passing the heated, freshly regenerated catalystas a gravity ilowing stream into the upper section of said conversionzone as aforesaid.

4. In a continuous process for endothermic conversions of fluidhydrocarbons at elevated temperatures in the presence oi a movingparticle form solid contact material, wherein the heat of reaction issupplied at least mostly by the contact material thereby requiring aninitial contact material temperature substantially above that at whichit can be practically mechanically conveyed the improved method whichcomprises: passing said contact material as a substantially compactcolumn downwardly through a confined conversion zone while contacting itwith said fluid hydrocarbons toeect the conversion thereof, whereby acarbonaceous contaminant is deposited on said contact material and thetemperature o i' said contact material is decreased due to heatadsorption by said conversion to a level below about 1100 F. maintaininga confined burning zone separate from and along side of said conversionzone, withdrawing spent contact material from said conversion zone andmechanically conveying said contact material upwardly to a locationsuitable for its flow into said burning zone, passing said spent contactmaterial as a substantially compact column downwardly through saidburning zone, passing a combustion supporting gas into contact with saidcontact material in said burning zone to effect burning of a substantialportion but less than all of said contaminant, passing. a separate heatexchange iluid in heat exchange relationship with said catalyst tocontrol its temperature during the contaminant burning below a heatdamaging level, withdrawing contact material from the lower section ofsaid burning zone bearing a residual contaminant deposit amounting to atleast 0.2 percent by weight of the contact material over and above thaton said contact material entering said conversion zone, controlling thetemperature of said contact material bearing said residual deposit at apractical mechanical conveying temperature which is below about 1100 F.and passing said contact material bearing said residual deposit to amechanical conveying zone, maintaining a moving column of said contactmaterial in a nal burning zone above said conversion zone, mechanicallyconveying said contact material bearing said residual deposit to alocation above said inal burning zone from which it may flow by gravityinto said nnal burning sone, ilowina said con.

tact material into the upper section of'said ilnal burning zone tosupply said column therein, contacting said contact material in saidfinal burning zone with a combustion supporting gas in the absence ofsubstantial heat removal by a heat exchange iluid to eilect burning otresidual contaminant on said contact material amounting to at leastabout 0.2 percent by weight, thereby heating said contact material to atemperature substantially above 1100 l". which is suitable for supplyingas sensible heat in the contact material at least the major portion ofthe heat required for the endothermic hydrocarbon conversion in saidconversion zone and flowing said contact material as a coniinedgravitating stream from said i'lnal burning zone to said conversion zoneto supply said column of contact material therein.

5. In a continuous process i'or endothermic catalytic conversions oi'fluid hydrocarbons to lower boiling hydrocarbons at elevatedtemperatures in the presence of a moving particle form solid catalystwherein at least the maior portion of the heat of reaction is suppliedas sensible heat in the catalyst charge thereby requiring a catalystcharge temperature substantially above that at which the catalyst can bepractically mechanically conveyed the improved method which comprises:introducing freshly regenerated catalyst into the upper section of aconilned conversion zone at a temperature above about 1000 F. andpassing said catalyst as a substantially compact column of gravitatingparticles downwardly through said confined conversion zone whilecontacting it with said iiuid hydrocarbons to effect the conversionthereof to lower boiling hydrocarbons whereby a carbonaceous contaminantdeposit forms on said catalyst and the catalyst is cooled to atemperature below about 1000 1". at which the catalyst may bepractically mechanicallyponveyed, maintaining a regeneration zone apartfrom said conversion zone, withdrawing spent catalyst from the lowersection of said conversion zone and mechanically conveying it to alocation from which it may ilow by gravity into the upper section ofsaid regeneration zone, passing said catalyst as a substantially compactcolumn downwardly through said regeneration zone, passing a combustionsupporting gas into contact with said catalyst to burn oi! a substantialportion but not all of said contaminant deposit while removing heatliberated by the contaminant burning by means of a separate heatexchange fluid, withdrawing partially regenerated catalyst from thelower section of said regeneration zone bearing more than about 0.2percent by weight but less than about 0.7 percent by weight contaminantmeasured as carbon over and above any contaminant deposit on the freshlyregenerated catalyst entering the'conversion zone, controlling thetemperature oi the partially regenerated catalyst below about 1000 F.and passing it to a mechanical conveying zone, maintaining a movingcolumn o! catalyst in a connned iinal burning zone above said conversionzone. mechanically conveying said catalyst bearing said residual depositto a location above said nnal burning sone from which it may ilow bygravity to said ilnal burning zone. :lowing said catalyst into the uppersection of said ilnal burning zone to supply said column therein,passing a combustion supporting gas into contact with said catalyst insaid ilnal burning zone, in absence of substantial heat removal by anyfluid heat exchange medium, at a controlled rate to effect burning ofresidual contaminant deposit from said catalyst amounting to less than0.7 percent by weight but more than 0.2 percent by weight of thecatalyst, measured as carbon, whereby the temperature of said catalystis increased to a level above about 1000 F. which will insure supply ofthe heat of hydrocarbon conversion as sensible heat in said catalyst andflowing said catalyst into said conversion zone as said freshlyregenerated catalyst as aforesaid.

6. A continuous process for conversion of high boiling liquidhydrocarbons to lower boiling hydrocarbon products in the presence of amoving particle form adsorbent catalyst which comprises: introducingfreshly regenerated catalyst containing a small residual deposit ofcarbonaceous material into the upper section of a conned conversion zoneat a temperature above about 1000 F. and Apassing said catalyst as asubstantially compact column downwardly through said zone, introducinghigh boiling liquid hydrocarbons into said conversion zone in contactwith said catalyst to effect conversion of said hydrocarbons to lowerboiling gasiform products, whereby a carbonaceous contaminant isdeposited on said catalyst and the temperature of said catalyst isdecreased, due to heat absorption by said hydrocarbon conversion, to a.level at which the catalyst may be practically mechanically conveyed,maintaining a regeneration zone apart from said conversion zone,withdrawing spent catalyst from the lower section of said conversionzone and mechanically conveying it to a location from which it may flowby gravity into the upper section of said regeneration zone, passingsaid catalyst as a substantially compact column downwardly throughsaid'regeneration zone, passing an oxygen containing gas under a backpressure vnear atmospheric pressure through said column of catalyst insaid regeneration zone to burn off a substantial portion but not all ofsaid contaminant deposit while removing heat liberated by contaminantburning by means of a separate heat exchange iluid, withdrawingpartially regenerated catalyst from the lower section of saidregeneration zone bearing more than about 0.2 percent by weight but lessthan about 0.7 percent by weight contaminant measured as carbon over andabove any contaminant deposit on the freshly regenerated catalystentering the conversion zone, passing the partially regenerated catalystat a practical mechanical conveying temperature to a mechanicalconveying zone, maintaining a moving column of catalyst in a confinednal burning zone above said conversion zone, mechanically conveying saidcatalyst bearing said residual deposit to a location above said finalburning zone from which it may ow by gravity to said nal burning zone,flowing said catalyst into the upper section of said final burning zoneto supply said column therein, passing a combustion supporting gas intocontact with said catalyst in said final burning zone, in absence ofsubstantial heat removal by any fluid heat exchange medium, at acontrolled rate to effect burning of residual contaminant deposit fromsaid catalyst amounting to less than 0.7 percent by Weight but more than0.2 percent by weight of the catalyst, measured as carbon, whereby thetemperature of said catalyst is increased to a level above about 1000 F.which will insure supply of the heat of hydrocarbon conversion assensible heat in said catalyst, controlling a back pressure on the gasin said final burning zone substantially above atmospheric so as toincrease the rate of contaminant 14 burning and flowing the catalystfrom said nal burning zone into said conversion zone as said freshlyregenerated catalyst as aforesaid.

7. A continuous process for conducting endothermic conversions of fluidhydrocarbons at elevated temperatures in the presence of a suitablecontact material consisting of particles of substantial size asdistinguished from powdered material which process comprises:introducing said contact material into the upper section of a confinedconversion zone at a temperature suitable for supporting the conversionof said iiuid hydrocarbons and for supplying at least most of the heatof reaction, passing said contact material downwardly through saidconversion zone while contacting it with said hydrocarbons to effect theconversion thereof with resultant deposition of a carbonaceouscontaminant deposit on said contact material, With,- drawing the usedcontact material from the lower section ofv said conversion zone andpassingit to a mechanical conveying zone at a temperature at which itmay be practically mechanically conveyed, maintaining a confined burningzone separate from said conversion zone, mechanically conveying saidused contact material to a location from which it may ow into saidburning zone, passing said contact material downwardly through saidburning zone, passing an oxygen containing gas into contact with saidcontact material at a low pressure which is near atmospheric pressure toburn off from said contact material in saidburning zone sulcientcontaminant deposit to reduce the residualideposit on said contact.material at least below about 0.7 percent carbon by weight of contactmaterial over and above the deposit on the contact material entering theconversion zone, passing the contact material bearing the residualdeposit from the lower section of said burning zone to a confinedconveying zone and controlling the .temperature of said contact materialpassing to said last named conveying zone at a y level at which thecontact material may be practically mechanically conveyed, maintaining aconned final burning zone above said conversion zone, conveying saidcontact material bearing said residual portion of the originalcontaminant deposit to a location from which it may flow. into saidfinal burning zone, passing said contact material through said finalburning zone in the absence of substantial heat removal by any heatexchange iluid, passing an oxygen containing gas into contact with thecontact material in said final burning zone andcontrolling the gaseouspressure throughout said zone substantially above the pressure in saidfirst named regeneration zone, controlling the amount of such gas flowsufficiently high to burn off from said contact material a sufficientamount of residual contaminant deposit to heat said contact material toa temperature substantially'above the average conversion temperature insaid hydrocarbon conversion zone and passing the'contact materialwithout intermediate cooling and by gravity flow from said nal burningzone into the upper section of said conversion zone as aforesaid.

8. In a continuous process for endothermic catalytic conversions ofiiuidhydrocarbons to lower boilingr hydrocarbons at elevatedtemperatures in the presence of a moving particle form solid catalystwherein at least the major portion of the heat of reaction is suppliedas sensible heat in the catalyst charge thereby requiring a catalystcharge temperature 'substantially above that at which the catalyst canbe practically mechanically conveyed the improved method whichcomprises: introducing freshly regenerated catalyst bearing a smallamount of residual carbonaceous deposit into the upper section of aconiined conversion zone at a temperature above about 1000 F. andpassing said catalyst as a substantially compact column o! gravitatingparticles downwardly through said confined conversion zone whilecontacting it with said duid hydrocarbons to etlect the conversionthereof to lower boiling hydrocarbons whereby a carbonaceous contaminantdeposit forms on said catalyst and the catalyst is cooled to atemperature below that maximum at above which it could not bepractically mechanically conveyed, withdrawing spent catalyst i'rom thelower section of said conversion zone and mechanically conveying it to acatalyst surge zone maintained apart from said conversion zone, nowingthe catalyst by gravity from said surge zone downwardly i through aseries of burning zones as a substantially compact column, passing anoxygen containing gas into contact with said catalyst in each of saidburning zones to burn oil' a portion of the contaminant deposit, passinga cooling heat exchange fluid in heat exchange relationship with saidcatalyst between burning zones to maintain the temperature oi' saidcatalyst below a heat damaging level, withdrawing catalyst from thelowermost burning zone still containing a residual deposit over andabove that, amount on the catalyst entering said conversionzone, whichdeposit is within the range about 0.2 to 0.7 percent carbon by weight ofthe catalyst, cooling the partially regenerated catalyst to a practicalmechanical conveying temperature, and mechanically conveying it to alocation spaced above said conversion zone, flowing the catalyst bygravity as a substantially compact column downwardly through a conilnedilnal regeneration zone, passing a combustion supporting gas intocontact with said catalyst in said ilnal burning 16 umn ot downwardlymoving catalyst particles in a conned conversion zone, passing a iluidhydrocarbon reactant into contact with said catalyst to eilect itsconversion to lower boiling hydrocarbon products whereby a carbonaceouscontaminant deposit is formed on said catalyst and the temperature oi'said catalyst decreases to a suitable practical mechanical conveyingtemperature which is below about 1000 F., withdrawing said lower boilinghydrocarbon products from said conversion zone separately of saidcatalyst, withdrawing used catalyst from the lower section or saidconversion zone. maintaining a regeneration zone apart from saidconversion zone. withdrawing spent catalyst from the lower section oi'said conversion zone and mechanically conveying it to a location fromwhich it may ilow by gravity into the upper section of said regenerationzone, passing said catalyst as a substantially compact column downwardlythrough said regeneration zone, passing an oxygen containing gas intocontact with said catalyst in said regeneration zone to burn ott fromsaid catalyst at least the major portion of but less than all of thecontaminant 2.5 depositformed on said catalyst in each pass passing thepartially regenerated catalyst from zone, in absence of substantial heatremoval by 4 any iluid heat-exchange medium, at a controlled rate toeffect burning of residual contaminant deposit from said catalystamounting to less than 0.7 percent by weight but more than 0.2 percentby weight of the catalyst, measured as carbon, whereby the temperatureof said catalyst is increased to a level above about 1000 F. which willinsure supply of the heat of hydrocarbon conversion as sensible heat insaid catalyst and ilowing said catalyst into said conversion zone assaid freshly regenerated catalyst as aforesaid.

9. In a continuous process for endothermic catalytic conversions ofiluid hydrocarbons to lower boiling hydrocarbons at elevatedtemperatures in the presence of a moving particle form solid catalystwherein at least the major portion of the heat of reaction is suppliedas sensible heat in the catalyst charge thereby requiring a catalystcharge temperature substantially above that at which the catalyst can bepractically mechanically conveyed the improved method which comprises:maintaining a substantially compact colthe lower section of saidregeneration zone cooled to a practical mechanical conveying temperatureto a second conilned mechanical conveying zone. maintaining a confinedsupply bed of catalyst a spaced vertical distance above said conversionzone, mechanically conveying said partially regenerated catalyst to alocation from which'it -may ilow onto said supply bed, passing an oxygencontaining gas through said supply bed in absence of heat removal fromsaid catalyst by separate cooling fluids to burn oi! a sufficient amountoi said residual deposit from said catalyst to heat said catalyst to atemperature substantially above the average conversion temperature insaid hydrocarbon conversion zone and substantially above a practicalmechanical conveying temperature, passing the catalyst withoutintermediate cooling downwardly from said supply bed into the uppersection of said conversion zone as a substantially compact elongatedconfined stream of gravitating particles, and maintaining a seal blanketof inert gas adjacent the lower end of said stream to prevent escape ofhydrocarbons through said stream.

SYLVANDER C. EASTW OOD.

REFERENCES CITED The following references are of record in the

